Platen and method of manufacturing the same



June 11,1940. B, L, SMWH 2,203,752

PLATEN Ann METHOD oF MANUACTURING 'um SAME Filed Nov. 12, 1938 INVENTOR amv s L YMA/v SM/T/-fv ATTORNEY '-Peieoied .luce 11, 1940 2,203,752-

UNITED @sTATEs AParri-:rrr orifice.

BurnsLyman Smith,.Los Angeles, Calif. Application November iz, 193s, seriai No. 240,017

5 Claims. (Cl. 197--14'0 This invention is of an. improvement in platens for writing machines, figuring machines and the like, the said improvement consisting in applying to such platens an entirely new writing surface, having many advantages over current practice. i

An object of the present invention is to eliminate noise to a greater degree than has been heretofore possible. l

A further object is a writing surface for a platen that has superior traction when new, with respect to paper used, which traction surface does not become measurably impaired in quality over a -long `continued period of use.

5 Still anotherobject is a writing surfacevtha-t by the manner of its application protects the rubberof the platen from oxidization, indenting and other deterioration due to age and use.

The foregoing and other objects which will be 0 apparentfrom the disclosure, constitute the pur-` poses of the present invention.

I have illustrated my novel platen by a drawing that accompanies and forms a part vof this application, showing a typical typewriter platen 5 which is described in detail, but I do not intend theV description as a, limitation of my invention, thescope of which is to be ascertained by the claims that follow thedescriptive part of this specification. 'I'his is in vpart the same as D my application, Serial No. 208,098, iiled May 16, 1938, which I have found necessary to drop for lack of proper disclosure. i

In the drawing- Fig. I is a broken part of a conventional type- 5 `writer platen of tubular form, with one end'sectioned:

Fig. II is an end view of the left hand end of Fig. I; and

Fig. III is an enlarged view of the upper left g hand portion of Fig. I, in an attempt to rmore clearly illustrate the suedetted surface of the perimeter and ends.

Further describing the drawing- The body of the platenis of rubber" as here- 5 in described, showing two concentric tubes of diftering resiliency, l and 2, as is well known. The

uneven line constituting the boundaries marked B represent the .actual surface, -but with .the roughness greatly exaggerated due to the 'limi` l tations of pen and ink to show a bed of exceedingly tine bers as described. vThe large Fig. II has been made to show a light dotted line, rep

resenting cement 4, with fibers having one por.

cement is much too great, due to the thickness of line required in an india ink drawing. 5 indicates the ibers.

I prefer to use the standard two layer platen as shown, having a cushion layer l inside and a harder layer 2 outside, rather than a platen the rubber portion of which is the samev throughout, though this is preferential only.

The word rubber as employed herein is intended to include natural and synthetic rubber as well f `as all compositions having the well known char-- acteristics of rubber' compositions.

In manufacturing a rubber platen, the last step is to mount the article on a mandrel and carefully grind the outside to size.

I take the freshly ground platen and apply a coating of rubber cement, or other suitable cementitious material, over the entire external suror the desired grade'of material may be obtained directly from natural or synthetic bersby processing. I'have found short bers from rayonvf y very satisfactory.

The application of4 the moers to the soft cement' i quantities of the material since better adhesion` appears to result.

When `the cement has taken up the ultimate quantity of ber that will adhere, it is cured by permitting the solvent of the cement to evaporate. When liquid rubber cement is used. that portion of it remaining after curing is rubber, practically unchanged asy to quality from the rubber which was originally dissolved to make the cement, viz. a rather soft, tough,'rubber of high purity. I am not limited to rubber cement, how-l ever. as other cementitious materials having the desired adhesive quality with respect to rubber, are probably equally good.

When thoroughly cured, the platen is brushed to remove all fibers that are not firmly adherent to the platen surface, which leaves a suedetted surface resembling fine, hard, close grained felt,

but with-a notably less amount of flberends on the surface.

The cover has great wearing quality,cis abe sorbent of noise, is highly tractive to paper used as ina typewriter and protects the surface of the platen against indentation and direct atmos.- phere contact. The quality of rubber remaining in the cement layer 'after curing as an exceedingly thin coating,A is apparently less aected by aging" than the `grade of rubber that must be used in the platen structure proper.

Since, as is well known, fibers of the sort described andused take dyes well, platens oi any desirablecolor "may beproduced, both-for apf-pearance and to identify the different grades of platen materials. To realize all of the. possible advantages of my surface, I coat the exposed v `ends of the platen as well as the perimeter.

It is characteristic of these improved 4platens that none of the original rubber surface of the platen proper or of the set and stiiened cement,

will be visible on, the surface of the platen if cement of proper consistency is used. The cement must be highly viscous but liquid enough to be self-leveling.

Having fully described my improved platen and the steps expedient to follow in making it, what I claim as new and desire to` secure by Letters Patent, isl V 1. As a new article of manufacture, a platen for a Writing machine comprising a body of4 re silient material so formed as to have at least one uniformwriting sub-surface, a thin layer oi?` cementitious material on said sub-surface and a dense, closely laid layer of brous flock-like and-a. dense coating of ock adherent to said cementitlous material andv partly embedded therein in such manner that ya felt-like writing surface is provided without any of the cementitious material or of the sub-surface being exposed.

3. A platen for a writing machine comprising a body of rubber that is provided with a uniformly cylindrical external surface, a uniform thin coating."l of vrubber cement on-said external surface and a uniform coating of short fibersy of wool or the like having one portion of each fiber embedded inthe coating of rubber cement and another portionv unattached and free to constitute a felt-like external writing surface.

4. The method of making a platen forl a writing machine which consists of forming a body with a. uniformly cylindrical external surface. uniformly coating said external surface with soft cement, applying fibrous flock to said cement coating while the same is softLuntil the entire Awriting surface has taken all of the flock that can be made tocohere therewith, drying the cement land removing the surplus unattached bers of flock.

5. The method of lbuilding up a writing surface on a platen for' a writing machine or the like, which consists of making a vresilient body member and providing it with a uniformlyvcylindricalwritingsub-s'urface, grinding said sub-4 surface, applying a thin layerof liquid cement to the same in viscous liquid form and immedi. 

